Description: The Heat Factory warmer is a soft, light-weight pouch containing an inert mixture of iron powder, charcoal, salt, water and vermiculite. When exposed to air, a natural exothermic reaction generates consistent and prolonged heat. The pouch is made of soft cloth lined with a very thin layer of porous plastic for maximum durability. The warmers are odorless, non-toxic and air-activated. Height (In): 6.5 Width (In): 5 Depth (In): .25 Weight: 1 oz. Heat Factory Large Warmers generate heat for up to 20 hours. All Heat Factory warmers are non-toxic, safe, and odorless. Large Warmers can be used in pockets, stadium cushions, sleeping bags, and many other Heat Factory accessories. With Heat Factory warmers you will NEVER BE COLD AGAIN!®